1. Field of the Invention
The present invention relates to a vehicle equipped with a leanable body frame and two front wheels.
2. Description of the Related Art
A known vehicle includes a body frame that leans in the left-right or left-and-right direction while the vehicle is cornering and two front wheels which are provided so as to be aligned side by side in the left-and-right direction of the body frame (for example, refer to Japanese Patent Unexamined Publication JP A-2005-313876, U.S. Design Pat. D547,2425, and Catalogo partidi ricambio, MP3 300 64102 ie LT Mod. ZAPM64102, Piaggio).
The vehicle equipped with the leanable body frame and the two front wheels includes a link mechanism. The link mechanism includes an upper cross member and a lower cross member. In addition, the link mechanism also includes a right side rod which supports the right end portions of the upper cross member and the lower cross member and a left side rod which supports the left end portions of the upper cross member and the lower cross member. The upper cross member and the lower cross member are supported on the body frame at their middle portions directly in front of a steering shaft. The upper cross member and the lower cross member are supported on the body frame so as to be turnable about axes extending in the front-rear direction or substantially in the front-rear direction of the body frame. The upper cross member and the lower cross member turn relative to the body frame as the body frame leans, such that the relative positions of the two front wheels in the up-and-down direction change. The upper cross member and the lower cross member are provided higher in the up-and-down direction of the body frame than the two front wheels with the body frame standing in an upright state.
The vehicle equipped with the leanable body frame and the two front wheels includes a right shock absorbing device to support the right front wheel so that the right front wheel is movable in the up-and-down direction of the body frame and a left shock absorbing device to support the left front wheel so that the left front wheel is movable in the up-and-down direction of the body frame. The right shock absorbing device is supported on the right side rod so as to be turnable about the axis of the right side rod. The left shock absorbing device is supported on the left side rod so as to be turnable about the axis of the left side rod. The vehicle disclosed in Japanese Patent Unexamined Publication JP A-2005-313876 further includes a handlebar, a steering shaft, and a turning transmission mechanism. The handlebar is secured to the steering shaft. The steering shaft is supported on the body frame so as to be turnable relative thereto. When the handlebar is steered, the steering shaft turns accordingly. The turning transmission mechanism transfers the turning motion of the steering shaft to the right shock absorbing device and the left shock absorbing device.
The vehicle equipped with the leanable body frame and the two front wheels includes a number of on-board components which are provided around the steering shaft. The on-board components include lamps such as a headlamp, a radiator, a reservoir tank, electric components such as a horn, a main switch of the vehicle, a storage box, a storage pocket and the like.
The vehicle disclosed in Japanese Patent Unexamined Publication JP A-2005-313876 includes a resisting force change mechanism. The resisting force change mechanism suppresses the leaning of the body frame and the change in relative position of the two front wheels in the up-and-down direction of the body frame by increasing a resisting force against the operation of the link mechanism.
In the vehicle disclosed in Japanese Patent Unexamined Publication JP A-2005-313876, the resisting force change mechanism includes a brake disc and a caliper. The brake disc is fixed to the upper cross member of the link mechanism. The caliper changes the resisting force exerted on the operating link mechanism by changing the frictional force between the caliper and the brake disc. The caliper is attached to a portion of the body frame which is situated above the upper cross member. The link mechanism operates when the resisting force exerted by the resisting force change mechanism is zero or small. When the resisting force exerted by the resisting force change mechanism is large, the operation of the link mechanism is prevented or stopped. When the resisting force exerted by the resisting force change mechanism is small, the brake disc and the upper cross member move together relative to the body frame.
Since the caliper and the disc brake are used and change the frictional force by using mechanical contact, it is easy to make the frictional force zero or very small. Because of this, the resisting force change mechanism which includes the caliper and the disc brake causes the link mechanism to operate smoothly when the resisting force exerted by the resisting force change mechanism is zero or small. On the other hand, since the caliper and the disc brake are used and change the frictional force by using mechanical contact, it is necessary to ensure a large area for the surface of the disc brake with which the caliper is brought into contact. This requires a large caliper and a large brake disc. As a result, the resisting force change mechanism is large in size.
The vehicle disclosed in Japanese Patent Unexamined Publication JP A-2005-313876 is equipped with the link mechanism which moves as the body frame leans around the steering shaft. In addition, the vehicle includes around the steering shaft the large resisting force change mechanism which operates as the body frame leans and the link mechanism operates. Because of this, in the vehicle equipped with the leanable body frame and the two front wheels, the resisting force change mechanism needs to be arranged so that the movable range of the link mechanism and the large movable range of the resisting force change mechanism do not interfere with each other. Further, when mounting the on-board components, the on-board components need to be provided so as to avoid interference with the movable range of the link mechanism and the large movable range of the resisting force change mechanism. Because of this, in the vehicle equipped with the leanable body frame and the two front wheels, the peripheral construction of the steering shaft tends to be large.